The Study Of Radiation Reliability Of GaN Material And HEMT

GaN materials have been proved as the best chose to manufacture electronics devices together with high temperature, large power and high frequency features due to their wide band-gap as well as excellent physical properties. So, GaN-based devices will be the best candidates for applications in National defense, Spaceflight and others military areas. There is no deep research about the influence of radiation environment on devices reliabilities in and out of home. In this thesis, the radiation damage in GaN-based material and HEMT have been carried out in both experimental and theoretical ways.Basing on the analysis of radiation damage results in GaN-based HEMT, we concluded that the radiation damage mechanisms in AlGaN/GaN HEMT is NIEL. The radiation induced defects appeared with radiation induced hetero-interface state charges and the surface charge induced by radiation, leading to a change in 2DEG density, mobility and threshold voltage.The radiation damage effect of AlGaN/GaN heterojunction and HEMT were investigated usingγray. The degradation effects were observed which are slightly increase in threshold voltage and little decrease in carriers density of heterojunction but bigger decrease in saturation drain current and transconductance of HEMT, degradation in gate characteristics of devices and increase in the channel resistance are larger after radiation. The channel resistance increased and completely annealed shown radiation induced surface charge is the key problem. A comparison of MOS-HEMT, passivated and unpassivated HEMT has been done to find the best construct for device.The radiation damage effect of GaN material and HEMT was investigated using proton radiation. After low irradiation flunce, we observed that increase in carrier density, deteriorate in surface morphology and increase in crystal lattice strain of GaN material. While at the high irradiation flunce, decreased drain current and transconductance and obvious shifted threshold voltage of HEMT were observed.The model for the AlGaN/GaN HEMT radiation damage mechanisms was built up. There important parameters including mobility, 2DEG density and threshold voltage were analyzed, mainly considered the effect by radiation induced surface charge, radiation induced accepter defects and interface charge.Some nuclear hardening ways were mentioned including field plate structure, improving the quality of material, passivation technology and energy band project.